Hand-held ejector-type dispensing systems have long been used for delivery of multiple-part silicone dental impression materials. The standard in the industry has heretofore been use of polypropylene as the material of choice for manufacture of the cartridge body, together with silicone O-rings on the plunger for applying force to extrude the material from the cartridge body. Devices useful for delivery of such materials include multiple barrel dispensing devices having a static mixer provided to efficiently mix the separate components as they are extruded from the barrels of the device. An example of such a device is described in U.S. Pat. No. 4,538,920 to Drake.
U.S. Pat. No. 5,100,320 discloses a cartridge for delivery of dental compositions. The material from which the cartridge is manufactured must have a burst strength greater than that of an otherwise identical cartridge made entirely of polypropylene and a 24 hour water absorption less than nylon-6. These materials are discussed at column 4, lines 3-12.